They make an unlikely duo. But after meeting at a reserve for endangered animals, Suryia the orangutan and Roscoe the Bluetick hound have become inseparable.

And now the pals have released a picture book capturing their unorthodox friendship.

The best friends were besieged by young fans as they held their own signing for the new release at a bookstore in Georgetown, South Carolina.

Best of friends: Suryia the Orangutan and Roscoe the dog at their book signing

Smile for the camera: But I do wonder if Cheetah and Rin Tin Tin got bored with book signings too?

A proper nana: Actually, I'd prefer something with a bit more pedigree, chum

Entitled Suryia And Roscoe, the book shows the pair enjoying each other's company at the South Carolina wildlife reserve where they met.
In one photo, a stubborn Roscoe refuses to eat a banana offered by his friend.

Another shows Suryia in a life jacket closely watching over Roscoe as he goes for a doggie-paddle.

And, as if posing for holiday snaps, they are also captured taking walks through the gardens and posing in front of an elephant.

The friends have garnered worldwide media attention, appearing in the National Geographic magazine and on the Oprah Winfrey and Ellen DeGeneres shows in the U.S.

They met four years ago when Roscoe followed staff from The Institute of Greatly Endangered and Rare Species (TIGERS) in Myrtle Beach as they walked home.

He was immediately spotted by the orangutan, who ambled over to make friends.

Dr Bhagavan Antle, the reserve's founder, said: 'Roscoe looked really thin and a little lost so we fed him and took care of him.

'He followed us through the gate and ran over and found Suryia. As soon as he saw Roscoe, Suryia ran over to him and they started playing.

'Dogs are usually scared of primates, but they took to each other straight away. We made a few calls to see if he belonged to anyone and when no one came forward, Roscoe ended up staying.'